1. Field of the Invention
The present invention relates to a polymeric fluorescent substance and a polymer light-emitting device (hereinafter, sometimes referred to as polymer LED) using the same.
2. Description of the Related Art
Unlike with low molecular weight light-emitting materials, polymeric light-emitting materials (polymeric fluorescent substance) are soluble in a solvent, and can form a light-emitting layer in a light emitting device by a coating method, consequently, have been variously investigated. In recent years, polymeric fluorescent substances having a fluorene unit attract attention, and in order to improve the performance, copolymers comprising a fluorene unit and other unit have been studied.
Among the above copolymers, a copolymer comprising an aromatic amine structure (hereinafter, may be referred to as aromatic amine unit) as other unit is disclosed, for example, a polymeric fluorescent substance comprising a copolymer which comprises a fluorene unit and an aromatic amine unit having a nitrogen atom in the main chain (WO 99/54385).
However, the above known polymeric fluorescent substance comprising a fluorene unit and an aromatic amine unit having a nitrogen atom in the main chain has a problem that luminance and light emitting efficiency are not yet sufficient, when the polymeric fluorescent substance is used as a light emitting layer.
An object of the present invention is to provide a polymeric fluorescent substance comprising a copolymer which has a substituent containing a specific aromatic amine structure in the side chain, and when said polymeric fluorescent substance is used for a light emitting layer, high luminance and high light emitting efficiency are attained, and to provide a polymer LED using the polymeric fluorescent substance.